WASHINGTON -- Ford Motor Co. is fighting a two-front battle -- one in a Florida court, the other with federal safety regulators -- to seal documents that suggest roof strength is key to protecting people in rollover crashes.

The conflict comes as the National Highway Traffic Safety Administration has sent a proposed update to the roof crush standard to the White House for review. The new rules are expected to be finalized later this year. Consumer activists are campaigning for stronger roof requirements.

Ford has asked a court in Florida to issue an order preventing the public from viewing crash reports from its Volvo subsidiary that showed engineers working to improve the roof structure and seat belts in the XC90 to make the SUV safer.

The documents were used at trial by lawyers for Claire Duncan, who was killed in a rollover crash involving a Ford Explorer.

Ford, which lost the case, said the Explorer's roof exceeded federal standards, and federal crash data show that the SUV is as safe as comparable vehicles.

Other documents used as evidence in the trial showed Ford engineers made the Explorer roof weaker during two vehicle redesigns in the 1990s.

Duncan's lawyers said Ford designed down to a minimum federal standard when it knew a stronger roof would have provided more safety.

The same documents used as evidence in the trial were placed in the public docket of the NHTSA on April 26. They were temporarily removed last week after Ford protested.

Ford says the papers contain corporate trade secrets. In an April 29 letter to NHTSA, Ford assistant general counsel Donald Lough wrote that widespread public access to the documents "would likely result in substantial competitive harm" by revealing how the company introduces new technologies.

The Detroit News first reported on the Ford and Volvo documents March 29, after a reporter obtained evidence used at the trial in Duval County Circuit Court. Other major media outlets have also reported on the documents.

Lawyers for the Duncan family said they would fight a request from Ford to put the evidence at the trial back under seal in a hearing scheduled for May 16. They contend that Ford's request would violate state law, which holds that court proceedings are public events.

"Our position is simple: If it was used as evidence, it is public information," said Raymond Reid, an attorney with Pajcic & Pajcic in Jacksonville.

Safety advocates said the Volvo engineering reports were especially damning, considering the longtime contention by Ford -- as well as General Motors Corp. and DaimlerChrysler AG's Chrysler Group -- that roof strength is not an important factor in rollover crashes.

The companies have argued for decades that occupants are killed or injured in rollover crashes because they fly out of their seats and "dive" into the roof as the vehicle turns over.

The Volvo test reports show that engineers in Sweden placed a high priority on roof strength, as well as improved safety belts, as Volvo developed its first SUV, the XC90. In one test report, dated August 1999, a crash-test dummy received severe head blows as the roof caved in.

After adjustments were made to the roof structure, as well as to the windshield, sun roof and seat-belt pretensioners, a dummy survived another test with minor injuries, according to a September 2000 test report.

"The combination of reinforced roof strength and more effective belt pretensioners were successful!" a Volvo memo stated.

The Ford documents, in contrast, outline how Ford's redesign of the Explorer between 1995 and 1999 resulted in the SUV meeting only minimum roof safety standards despite the concern of some engineers, according to internal e-mails from October 1999 unsealed during the trial.

Sean Kane, the auto safety consultant who submitted the Ford documents to NHTSA, said he wanted the public to see another set of data that showed a correlation between injury and roof strength.

"Ford and Volvo both say they're safe vehicles, but here's an area where there is no information available to a consumer," said Kane, president of Safety Research and Strategies, a Massachusetts legal services firm. "I would hope the agency would see what's missing in the whole debate is how well a vehicle holds up in a rollover crash."

Ford is appealing the $10.2 million jury verdict in the Duncan case.

NHTSA spokesman Rae Tyson said the agency took the documents down temporarily, and it is waiting for a full legal argument from Ford about why they should not be available to the public. That could happen in the next few days, Ford's lawyers say.

"We will make them publicly available if at all possible," Tyson said. "At the same time, we have a manufacturer who is making an argument about why they should be confidential. We're going to give them an opportunity to be heard."

Separately on Monday, federal officials told a Society of Automotive Engineers gathering in Washington they were researching ways to protect people in rollover crashes that go beyond stronger roofs.

Officials at NHTSA's test track in Marysville, Ohio, said they were looking at tests to measure the effectiveness of side air bags in preventing ejections in rollovers.